Triazinethiol and alkenyl-containing organopolysiloxane, making method, and primer composition comprising same

Abstract

An organopolysiloxane having triazinethiol and alkenyl radicals in a molecule and a primer composition comprising the same are provided. The primer composition assists in establishing a high bond strength between metal and silicone rubber by the mechanism that the triazinethiol moieties form strong chemical bonds with a difficult-to-bond metal such as gold, silver or copper, and the alkenyl moieties are involved in silicone rubber vulcanization.

1. An organopolysiloxane having triazinethiol and alkenyl radicals in a molecule. 
     
     
       2. The organopolysiloxane of  claim 1  having the siloxane unit formula (1):
   (R 1 R 2 R 3 SiO 1/2 ) a (R 4 R 5 SiO 2/2 ) b (R 6 SiO 3/2 ) c (SiO 4/2 ) d (O 1/2 X) e   (1) 
 
       wherein X is hydrogen or C 1 -C 4  alkyl,
 R 1  to R 6  are optionally substituted C 1 -C 6  alkyl, C 2 -C 10  alkenyl or C 6 -C 10  aromatic hydrocarbon, any one or more of R 1  to R 6  contains at least one alkenyl radical and at least one radical of the structural formula (2): 
 
       
         
           
           
               
               
           
         
       
       wherein A is a divalent organic radical having one end attached to the triazine ring and another end attached to a silicon atom in the polysiloxane,
 the subscripts a, b, c, d and e are numbers which are on the average in the range: 0<a≦0.8, 0<b≦1, 0≦c<1, 0≦d≦0.4, and 0≦e≦0.5, and a+b+c+d=1. 
 
     
     
       3. The organopolysiloxane of  claim 2  wherein the organic radical -A- in structural formula (2) is a divalent hydrocarbon radical which may be interrupted by carbonyl carbon or a heteroatom selected from oxygen, sulfur and nitrogen. 
     
     
       4. The organopolysiloxane of  claim 3  wherein the organic radical -A- in structural formula (2) is —CH 2 CH 2 CH 2 NH— or —CH 2 CH 2 CH 2 NHCH 2 CH 2 NH—. 
     
     
       5. The organopolysiloxane of  claim 1  wherein the alkenyl radical is selected from the group consisting of vinyl, allyl, butenyl, pentenyl, hexenyl, and cyclohexenyl. 
     
     
       6. A method for preparing an organopolysiloxane having triazinethiol and alkenyl radicals in a molecule, comprising the step of reacting an organopolysiloxane having amino-functional and alkenyl radicals on side chains with triazine trithiol. 
     
     
       7. The method of  claim 6  wherein the amino-functional radical is 3-aminopropyl or N-(2-aminoethyl)-aminopropyl. 
     
     
       8. A primer composition for adhesion comprising (A) an organopolysiloxane having triazinethiol and alkenyl radicals in a molecule and (B) an organic solvent. 
     
     
       9. The primer composition of  claim 8  wherein the organopolysiloxane (A) has the siloxane unit formula (1):
   (R 1 R 2 R 3 SiO 1/2 ) a (R 4 R 5 SiO 2/2 ) b (R 6 SiO 3/2 ) c (SiO 4/2 ) d (O 1/2 X) e   (1) 
 
       wherein X is hydrogen or optionally substituted C 1 -C 4  alkyl,
 R 1  to R 6  are C 1 -C 6  alkyl, C 2 -C 10  alkenyl or C 6 -C 10  aromatic hydrocarbon, any one of R 1  to R 6  contains at least one alkenyl radical and at least one radical of the structural formula (2): 
 
       
         
           
           
               
               
           
         
       
       wherein A is a divalent organic radical having one end attached to the triazine ring and another end attached to a silicon atom in the polysiloxane,
 the subscripts a, b, c, d and e are numbers which are on the average in the range: 0<a≦0.8, 0<b≦1, 0≦c<1, 0≦d≦0.4, and 0≦e≦0.5, and a+b+c+d=1. 
 
     
     
       10. The primer composition of  claim 9  wherein the divalent organic radical -A- in structural formula (2) is a divalent hydrocarbon radical which may be interrupted by carbonyl carbon or a heteroatom selected from oxygen, sulfur and nitrogen, having one end attached to the triazine ring and another end attached to a silicon atom in the polysiloxane. 
     
     
       11. The primer composition of  claim 10  wherein the divalent organic radical -A- in structural formula (2) is —CH 2 CH 2 CH 2 NH— or —CH 2 CH 2 CH 2 NHCH 2 CH 2 NH— having one end attached to the triazine ring and another end attached to a silicon atom in the polysiloxane. 
     
     
       12. The primer composition of  claim 8 , further comprising (C) an organic titanate. 
     
     
       13. The primer composition of  claim 8 , which is used for adhesion of silicone rubber. 
     
     
       14. The primer composition of  claim 13 , which is used for adhesion between a metal and a cured product of a millable silicone rubber composition.